The ketogenic diet is a “fast mimicking” diet intended to keep your body in the metabolic state of ketosis indefinitely. If you are in relatively good health apart from your cancer, and have excess body fat to burn, you can consider pursuing periods of water-fasting to further stress your cancer cells.
Note, this is not a “cleanse”. Very different from juice-cleanses or other such things (such as the Gerson protocol), a water-fast is exactly that, water only. Drinking constant quantities of juice is NOT what we are doing here.
Great articles from Paleo Leap: Intermittent Fasting
Be sure to stay hydrated. Ketosis requires extra water, so be sure to drink lots while fasting.
If you have epilepsy consult with a doctor. Suddenly starting a water fast is dangerous for people with epilepsy. You will need to ‘ease’ into it using an increasingly restrictive keto diet.
Here is a podcast interview of Dr. Seyfried in which he discusses water fasting. “Water fasts as a potential tactic to beat cancer” - The Quantified Body